The invention relates to a method and a system for monitoring an adaptive network having respective network nodes and network connections between the network nodes, the network nodes each having a transceiver which is coupled with a respective network connection.
Modern motor vehicles have a plurality of regulating and control devices and, furthermore, also a plurality of sensors which, for example, may also one or more video cameras, and devices for the purpose of information transmission or entertainment of vehicle occupants, such as a radio and/or a video playback device. Furthermore, navigation devices are also regularly used in modern motor vehicles. An efficient operation of these devices requires a data transmission system with a high data transmission rate.
Up to now, different bus systems have frequently been used in motor vehicles, such as the Local Interconnect Network (LIN), the Controller Area Network (CAN) or the FlexRay. With an increasing complexity of the regulating and control devices and with a growing number of the above-mentioned devices, the demand for networks, which have an expanded protocol range, for example, the need for Ethernet networks, is rising. Such networks, for example, according to the Ethernet standard, are adaptive in the sense that they can compensate certain interference influences, which, for example, may be caused by an interference irradiation onto the network connection between the respective network nodes. This makes them particularly interesting for use in motor vehicles.
However, particularly for the use in motor vehicles, it is desirable for networks to operate reliably but, on the other hand, to also avoid units being subjected to an undesirable interference such as by a possibly occurring interference radiation.
It is an object of the invention to provide a method and a system for monitoring a network, which reliably detects, or detect faults in, the network connection between network nodes.
This and other objects are achieved by a method, and corresponding system, for monitoring an adaptive network having respective network nodes and network connections between the network nodes. The network nodes each have a transceiver, which is coupled to a respective network connection. The transceiver is designed for providing a mean error value, which is representative of deviations of a received signal from predefined reference signal values. In a reference operating state of the adaptive network, a respective reference error value is determined as a function of the average fault value provided by the respective transceiver. In at least one predefined operating state of the adaptive network, a respective actual error value is determined as a function of the mean error value provided by the respective transceiver. And, as a function of the respective reference error value and the assigned actual error value, it is determined whether a fault is present in the respective network connection which is coupled with the respective transceiver.
The invention is distinguished by a method and a corresponding system for monitoring an adaptive network with respective network nodes and network connections between the network nodes. The network nodes each have a transceiver which is coupled to a respective network connection. The respective transceiver is designed for providing a mean error value which is representative of deviations of a received signal from predefined reference signal values. In a reference operating state of the adaptive network, a respective reference error value is determined as a function of the mean error value provided by the respective transceiver. The reference operating state may, for example, exist when a motor vehicle, in which the adaptive network is arranged, is quasi finished, and is therefore, for example, situated at the end of the conveyor belt. The respective reference error value can then easily be determined in this manner.
In addition, in at least one predefined operating state of the adaptive network, a respective actual error value is determined as a function of the mean error value provided by the respective transceiver. Depending on the respective reference error value and the assigned actual error value, it is determined whether a fault is present in the respective network connection which is coupled with the respective transceiver. The predefined operating state and the reference operating state differ from one another.
On the one hand, in this manner, the advantage of the adaptive network can be utilized for compensating interferences which are caused, for example, by an interference irradiation onto the network connection between the network nodes; and, on the other hand, faults can be detected in the respective network connection which are caused, for example, by a poor cable connection, as a result of, for instance, aging and/or corrosion. In this fashion, the respective faulty component can then easily be identified and, if necessary, exchanged and/or repaired. It can thereby be avoided that, for example, also as a result of a changed radiation behavior of the network connections caused by the respective fault and/or a corresponding adaptation for the compensation of the fault, undesirably high interference radiations occur in the area of the network connection which, for example, may have reactive effects on other units, as, for example, interfere with radio reception.
According to an advantageous further development, a fault in the respective network connection will be recognized as a function of whether the amount of the deviation between the respective reference error value and the assigned actual error value exceeds a predefined threshold value. In this manner, the fault can easily but nevertheless reliably be recognized arithmetically.
In a further advantageous development, in the at least one predefined operating state, the then provided error value will be used for adapting the respective actual error value. In this fashion, the actual error value can easily be filtered, and brief outliers of the provided mean error value will not necessarily result in a detection of the fault in the respective network connection which then may possibly not have been correctly assigned. In this context, particularly the recognition is utilized that faults in the respective network connection are not reflected by a briefly deteriorated mean error value but rather by the latter correspondingly deviating from the reference error value for an extended period of time.
In this connection, it is particularly advantageous for the adaptation of the respective actual error value to be carried out in the form of a sliding average. This can be implemented particularly easily arithmetically, and results in a desired smoothing of the course of the actual value, which is advantageous with respect to a reliable recognition of a fault in the respective network connection.
In a further advantageous development, the respective provided mean error value is a quadratic mean error value.
According to a further advantageous development, the mean error values are corrected by means of a predefined filtering function as a basis for determining the respective reference error value and/or the respective actual error value. A contribution can thereby be made to preventing small deviations in the line quality of the network connection possibly resulting in undesirably large deviations of the respective mean error value. The predefined filtering function may, for example, comprise a linear quality function which may possibly be dependent on a transceiver type or a transceiver manufacturer or an installation site in the motor vehicle.
According to a further advantageous development, the adaptation of the respective actual error value takes place as a function of a predefined weighting of deviations of a predefined extent in the case of the mean error values or the mean error values corrected by means of the predefined filtering function.
According to a further advantageous development, it is checked in the reference operating state of the adaptive network whether the respective reference error value is in a predefined reference value range and, if that is not so, a fault is detected in the network connection or the respective network node. In this manner, it can easily be ensured that an already initially faulty adaptive network is at first considered to be fault-free.
According to a further advantageous development, the predefined operating state is a starting operation correlating with an engine start of a motor vehicle, in which the network is arranged. In this manner, a check can in each case easily take place at meaningfully predefined intervals concerning the presence of the fault in the respective network connection.
According to a further advantageous development, the predefined operating state is correlated with a change of a connection status of the respective network connection from a link-up status to a link-down status or vice-versa.
According to a further advantageous development, the predefined operating state is present in that those network nodes that are situated at the end points of the respective network connection have a predefined functional network node operating state.
According to a further advantageous development, the predefined operating state depends on the fact that at least one predefined vehicle function has a predefined state outside the network. The predefined vehicle function is, for example, characteristic of whether a source of particularly high electro-magnetic interferences is either active or inactive in the proximity of the respective network connection. This contributes to obtaining a respective reproducible mean error value.
According to a further advantageous development, the adaptive network is Ethernet-based. This has the advantage that the Ethernet protocol is highly effective; it permits, for example, a data transmission of up to 100 Mbit/s. Furthermore, such a network can be implemented particularly cost-effectively, particularly in the context of network connections corresponding to UTSP (Unshielded Twisted Single Pair) which can comprise regular cost-effective cables and plug contacts.
According to a further aspect, a process and a corresponding system are provided for monitoring the adaptive network, wherein a respective reference error value (MSE_REF) is provided. In at least one predefined operating state of the adaptive network as a function of the mean error value provided by the respective transceiver, a respective actual error value is determined. As a function of the respect reference error value and the assigned actual error value, it is determined whether a fault is present in the respective network connection, which is coupled with the respective transceiver.
This particularly has the advantage that a learning of the reference fault value in the reference operating state will not be necessary. Thus, a checking of the network connection, as required, can already take place at the start of the operation and, as required, a fault can already be recognized at the point-in-time of the start of the operation, thus, for example, at the manufacturing facility of the vehicle. This approach may be particularly advantageous when, in the context of the predefined filtering function, the corrected mean error values are such that they assume only a narrowly limited number of values, for example, in the form of traffic light values “red”, “yellow”, “green”. The value assignment of the corresponding actual error values will then also take place correspondingly.
In this manner, a contribution will also be made to avoiding a later impaired fault detection possibility if, during the determination of the reference error value, an unrecognized fault was present in the reference operating state.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.